1. Field of the Invention
The present invention is directed at an N-acetyl amino acid racemase (AAR) from Amycolatopsis orientalis subspecies lurida, as well as the gene coding for it, and at plasmids, vectors, and microorganisms containing the gene.
2. Discussion of the Background
Using N-acetyl amino acid racemases, it is possible to obtain optically pure amino acids at a yield of 100% from the corresponding protected racemic N-acetyl amino acids, in interaction with acylases. Optically pure amino acids are used in parenteral feeding as well as for the production of chiral bioactive substances.
N-acetyl amino acid racemases (AAR) from Streptomyces atratus Y-53 (Tokuyama et al, Appl. Microbiol. Biotechnol. 1994, 40, 835-840) and Amycolatopsis sp. TS-1-60 (Tokuyama et al., Appl. Microbiol. Biotechnol. 1995a, 42, 853-859) are already known.
The AAR from Amycolatopsis sp. TS-1-60 has a strong dependence on cobalt and manganese ions with regard to its activity. The addition of these heavy metal ions to the synthesis stock is a disadvantage on a large technical scale, from the aspect of environmental protection.
It is an object of the present invention to provide an AAR that has a lesser activity dependence on heavy metal ions, as compared with the AAR from Amycolatopsis TS-1-60.
Another object of the invention to provide a gene coding for this enzyme.
Another object of the invention to provide a plasmid, vecor and microorganism that contain the AAR gene.
Another object of the invention to provide a primer for the AAR gene.
Another object of the invention to provide a gene probe for detecting the AAR gene.
Another object of the invention is to provide a process for producing enantiomer-enriched amino acids. BRIEF DESCRIPTION OF THE DRAWINGS
A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following Figures in conjunction with the detailed description below.
FIG. 1: Plasmid pAAR1-21I.
FIG. 2: Restriction card of the 2.5 kb EcoR1 fragment with the AAR gene.
FIG. 3: Plasmid pAAR2-21I.
FIG. 4: Plasmid pAAR3-21I.
FIG. 5: Effect of pH on AAR activity.
FIG. 6: Effect of Co2+, Zn2+, Mn2+ and Mg2+ concentration on AAR activity.
FIG. 7: Effect of Co2+, Zn2+, Mn2+ and Mg2+ concentration on AAR activity.
FIG. 8: Effect of N-acetyl-D-methionine concentration on AAR activity.